The Stable Isotope and Metabolomics Core Facility (Core xx) will provide at least two projects of this Program Project a comprehensive metabolomics facility that will assist the investigators in global metabolite and biosynthetic rate analyses required for the investigators to analyze the metabolomic "signatures" ofthe radiation injury process, as well as assess how these "signatures" are modified by disruptions of significant signaling pathways involved in radioprotecfion and sensitization. These metabolomic "signatures" will be related to the pertinent pathophysiology by the investigators ofthe individual projects, who will work closely with the Metabolomics Core to refine metabolite profiles, and biosynthetic rate profiles, needed for the elucidafion of the metabolic effects, and contributions to, the underlying pathophysiology. The core will provide advice on protocol design, preparation and processing of samples, as well as on the techniques and procedures available for the different studies. The services offered by the Core can evaluate : 1. Cellular/Organelle mitochondrial respiration and glycolysis rates in a 96 well plate format (Seahorse Biosciences Flux Analyzer);2. Metabolite quantification (GC/MS and/or LC/MS based);3. Stable isotope (deuterated water) evealuafion of protein and lipid biosynthefic rates. Note that both flux characterizafion, and metabolite profiling yield cellular metabolic 'signatures'that can be used for empirical classification of fissue models. When used in conjunction with each other, these empirical 'signatures'of flux and metabolites can also yield powerful physiologic assessments of cellular metabolism, and can point to compensations in metabolic pathways that are crucial to the maintenance of tumor cell metabolism that may be amenable to therapeutic attack. The kev personnel of the core will be the director and the Metabolomics Core technical staff. The director will be responsible for supervising all the acfivifies of the core, offering advice on the different methods and procedures, interpretation ofthe results, and generating Metabolomics reports and interpretations ofthe data. The technical staff will prepare and process tissue samples as appropriate for the study at hand, and perform some of the specialized techniques and procedures, such as metabolite discovery and quantificafion (using liquid chromatography (LC)/tandem mass spectrometry (Waters Xevo triple quadrapole), LTQ-Orbitrap, and gas chromatography (GC)-fime of flight (Waters GCT) mass spectrometry(MS)), and lipid and total protein biosynthefic rate assessment using deuterated water, by GCMS. Significance: Evaluation of metabolomics "signatures" is essential to the in vivo radiation-induced injury projects in this Program Project as it allow the study of the in vivo impact of disturbances in metabolic processes affected by radiation-induced injury, as well technologies developed to effect the outcome of radiation-induced injury.